In recent years, an optical image measuring technique of forming images that show the surface morphology and internal morphology of measured objects by using a light beam from a laser light source or the like has attracted attention. Unlike an X-ray CT apparatus, the optical image measuring technique is noninvasive to human bodies, and is therefore expected to be utilized more particularly in the medical field and biological field.
Patent Document 1 discloses a device to which the optical image measuring technique is applied. This device has such a configuration that: a measuring arm scans an object by a rotary deflection mirror (a Galvano mirror); a reference arm is provided with a reference mirror; and an interferometer is mounted at the outlet to analyze, by a spectrometer, the intensity of an interference light of light fluxes from the measurement arm and the reference arm. Moreover, the reference arm is configured to gradually change the light flux phase of the reference light by discontinuous values.
The device of Patent Document 1 uses a technique of so-called “Fourier Domain OCT (Optical Coherence Tomography).” That is to say, the device radiates a low-coherence light beam to a measured object, superposes the reflected light and the reference light to generate an interference light, and acquires the spectral intensity distribution of the interference light to execute Fourier transform, thereby imaging the morphology in the depth direction (the z-direction) of the measured object.
Furthermore, the device described in Patent Document 1 is provided with a Galvano mirror that scans with a light beam (a signal light), and is thereby configured to form an image of a desired measurement target region of the measured object. Because this device is configured to scan with the light beam only in one direction (the x-direction) orthogonal to the z-direction, an image formed by this device is a two-dimensional tomographic image in the depth direction (the z-direction) along the scanning direction (the x-direction) of the light beam.
Patent Document 2 discloses a technique of scanning with a signal light in the horizontal direction and the vertical direction to form a plurality of two-dimensional tomographic images in the horizontal direction, and acquiring and imaging three-dimensional tomographic information of a measured range based on the tomographic images. As the three-dimensional imaging, for example, a method of arranging and displaying a plurality of tomographic images in the vertical direction (referred to as stack data or the like), and a method of executing a rendering process on a plurality of tomographic images to form a three-dimensional image are considered.
Patent Documents 3 and 4 disclose other types of optical image measuring devices. Patent Document 3 describes an optical image measuring device that images the morphology of a measured object by scanning the measured object with light of various wavelengths, acquiring the spectral intensity distribution based on an interference light obtained by superposing the reflected lights of the light of the respective wavelengths on the reference light, and executing Fourier transform. Such an optical image measuring device is called a Swept Source type or the like.
Further, Patent Document 4 describes an optical image measuring device that radiates a light having a predetermined beam diameter to a measured object and analyzes the components of an interference light obtained by superposing the reflected light and the reference light, thereby forming an image of the measured object in a cross-section orthogonal to the travelling direction of the light. Such an optical image measuring device is called a full-field type, en-face type or the like.
Patent Document 5 discloses a configuration in which the OCT technique is applied to the ophthalmologic field. Before the optical image measuring device was applied to the ophthalmologic field, a fundus oculi observing device such as a retinal camera had been used (for example, refer to Patent Document 6).
A fundus oculi imaging device using the OCT technique has a merit that a tomographic image and three-dimensional image of the fundus oculi can be acquired, as compared with a retinal camera that merely images the fundus oculi surface from the front. Therefore, contribution to increase of the diagnosis accuracy and early detection of a lesion is expected.    Patent Document 1: Japanese Unexamined Patent Application Publication No. 11-325849    Patent Document 2: Japanese Unexamined Patent Application Publication No. 2002-139421    Patent Document 3: Japanese Unexamined Patent Application Publication No. 2007-24677    Patent Document 4: Japanese Unexamined Patent Application Publication No. 2006-153838    Patent Document 5: Japanese Unexamined Patent Application Publication No. 2008-73099    Patent Document 6: Japanese Unexamined Patent Application Publication No. 9-276232